There would be no "material impact" if Tullow exercised its right of first refusal over the oil blocks for sale, chief financial officer Paul Atherton said yesterday. London-based Tullow has until January 17 to pre-empt the offer.

Heritage agreed in November to sell Eni its 50pc interest in Blocks 1 and 3a in Lake Albert for $1.5bn (€1.04bn).

Tullow owns the other 50pc of both blocks and has said it may buy the stakes.

Offer

Tullow would "have to pre-empt on the same terms and conditions as Eni", Mr Atherton said, adding that the timetable for completion of the sale in the first quarter would remain unchanged.

There was also the possibility of a "superior offer" from another party, he said.

Heritage Oil jumped 4.3pc to 472.5p in London trading, the highest close since November 23, after Mr Atherton said the company would be able to buy back shares with some of the proceeds from the sale.